This invention relates generally to propulsion and steering devices for conventional wheelchairs. More specifically, the instant invention is directed to a device which lends itself to facile and ready attachment to a plurality of different types of wheelchairs irrespective of their construction, the attaching area therefore being generic to different types of wheelchairs. Additionally, a steering and propulsion device is provided which reliably allows the person constrained within the wheelchair to propel and steer in a predictable and safe manner providing the occupant of the wheelchair with a reliable and safe means for encountering various types of terrain. A further feature of the instant invention relates to an ability to adjust the frame in a plurality of dimensions so as to accommodate people of different configurations, and also to provide a means for folding the frame so as to effect compact storage.
With the increasing awareness of the rights of minorities in general, buildings, jobs, and the like have been made accessible to handicapped people. In this regard, those devices which afford a higher degree of self reliance have been particularly well received in the handicapped community, for the obvious attendant benefits. To this end, there has existed a long felt yet heretofore unsatisfied need to provide handicapped people with a means for reliably traversing somewhat moderate distances. For relatively short distances, the conventional configuration of the wheelchair has been found adequate; for extremely long trips, self contained vehicles such as automobiles have been modified in such a manner to allow the handicapped access thereto. It is for the intermediate distances as well as the short range distances that the instant application is directed. When encountering relatively steep terrain, prior art wheelchair devices do not lend themselves readily to facile manipulation, and the steering mechanisms of conventional wheelchairs eludes many an occupant's attempt at nimble manipulation, particulary at higher speeds. Additionally, traveling in a conventional wheelchair where the propulsion means is in intimate contact with the major support wheel allows contamination of the person's hands during inclement weather, an undesirable phenomena.
The following citations reflect the state of the art of which applicant is aware insofar as these citations appear to be germane to the patent process:
U.S. Pat. No. 3,309,110, Bulmer; PA0 U.S. Pat. No. 3,381,973, Carr; PA0 U.S. Pat. No. 3,666,292, Bartos; PA0 U.S. Pat. No. 3,848,891, Vittori; PA0 Publication-Across Campus Across Town-Orthopedic Systems Inc. 1980 Publication-Profiles-June 1980.
The two publications provide known prior art devices in which a front steerable wheel is provided, attached to the wheelchair in such a manner as to elevate the forwardmost castor wheels on a conventional wheelchair. Each device may be characterized in that it borrows extensively from conventional bicycle structure, and is neither foldable for easy storage nor adjustable to accommodate a plurality of different types of wheelchairs. More specifically, the device called "Unicycle" attaches only to a standard "Everest-Jennings" chair with no modifications. There are no adjustment means to alter the steering and propelling area relative to the user of the device, and a single chain extends from the steering head down to the driving hub which includes a derailer, it being noted that it is a rare engineering feat to have the driving wheel and the steering wheel coincident in conventional bicycles. Therefore, the "Unicycle" exhibits unwanted chain torsion which leads to throwing the chain. Similarly, the citation in "Mother Earth News" provides a wheelchair in which the propelling and steering member is not relatively adjustable in its relationship to the occupant, and a pair of mounting wings are located on opposed lateral extremities of the occupant proximate to the calf area, making ingress and egress into the device extremely difficult, particularly for people whose handicap includes immobility of the lower extremities. Clearly, this device is not readily adjustable to a plurality of different sized wheelchairs as is the instant invention. Other problems in this citation include the long moment arm that extends from the hand pedals to the steering fork which requires an exaggerated turning motion by the occupant, increasing the likelihood that at least one of the occupant's hands must disengage the device to complete a turn, an unwanted phenomena, coupled with the tendency in both of these citations to expose the occupant to the chain and sprocket area, a needless danger.
Although various other known prior art devices have attempted to address one or more shortcomings noted hereinabove, they too exhibit design problems of their own. For example, while the Carr patent appears to supply a greater degree of safety in excluding the occupant from the chain drive, this device would clearly not lend itself to nimble, agile motion at a higher rate of speed as does the instant application, and this citation appears to provide a complete living area for an invalid, thereby dictating the associated structure. Therefore, any similarities between the instant invention and this citation appears to be merely coincidental.
The patent to Vittori teaches the use of another known front wheel drive device for use by paraplegics, which while recognizing some of the pleasures and advantages capable of being derived by a front wheel drive mechanism, does not lend itself to be adapted to affixion to a conventional known prior art wheelchair, but rather requires a completely new vehicle. Therefore, the only similarity between this citation and the instant invention would be the coincidental structure similarity of the drive propulsion mechanism, the steering mechanism being functionally dissimilar.
The remaining two prior art devices, the patents to Bulmer and Bartos each teach the use of occupant propelled wheelchairs, in which the enlarged rear wheel of a conventional wheelchair is the drive mechanism, causing hand manipulation of appropriate length levers to provide rotation of the large wheel. It should be apparent that the steering mechanism associated therewith is somewhat unnatural when compared to the steering mechanism according to the instant invention, since the relative manipulation of the lever associated with the rear drive wheel also provides the direction altering capabilities. Thus, it can be seen that steering, particularly at a relatively high rate of speed could not be achieved as readily as with conventional steering mechanisms.
The instant invention is distinguished over the prior art citations in that a propulsion and steering device has been provided adapted to engage any of a plurality of conventional wheelchairs and includes a frame, attaching means for affixing the frame to the conventional prior art known wheelchair, steering and propelling means forming a part of the frame which includes a single steerable wheel, a folding means formed on the frame to collapse the frame for convenient storage and transport, and a plurality of adjustment means on the frame to allow different components of the propulsion and steering device to be relatively adjusted so that people of diverse dimensions can all be accommodated by one device particularly as set forth in the instant application.